Plasma polymerized polysiloxane membrane

Abstract

An ultrathin selectively permeable membrane made by glow discharge plasma polymerization of a single siloxane monomer with the deposition of the polymer as a single layer upon a nonporous support material. The resulting membrane has an oxygen content between about 10% and 60% and is highly permselective. The support material can be an electrode, thereby forming an electrode that is resistant to fouling or contamination but readily accessible to oxygen.

What is claimed is: 
     
       1. An oxygen sensing device, comprising: at least three electrodes, including a working electrode and a reference electrode;   means for creating an electric potential between the working electrode and the reference electrode; and   a permselective membrane formed upon the three electrodes by polymerizing a silicon-containing monomer directly onto the electrode;   the silicon-containing monomer having the general formula   R.sub.1 --Si--O--Si--R.sub.2 ;       wherein R 1  and R 2  are selected from the group consisting of --(CH 3 ) 3     --O--(CH 2 ) n  --CH 3 , where n=0 to 5,   --CH 2  --C 6  H 5 ,   --C 6  H 5 ,   --(CH 2 ) n  --COOH, where n=0 to 5,   --CO--(CH 2 ) n  --CH 3 , where n=0 to 5, and   --(CH 2 ) n  --CH 3 , where n=0 to 5.     
     
     
       2. The oxygen sensing device of claim 1 wherein at least one of the electrodes comprises metal. 
     
     
       3. The oxygen sensing device of claim 2 wherein the metal is selected from the group consisting of platinum, gold, silver, tungsten, iridium, palladium, tantalum and alloys thereof. 
     
     
       4. The oxygen sensing device of claim 3 wherein the metal comprises platinum. 
     
     
       5. The oxygen sensing device of claim 1 wherein at least one of the electrodes comprises carbon. 
     
     
       6. The oxygen sensing device of claim 1 wherein the membrane has an oxygen content of at least 20% by weight. 
     
     
       7. The oxygen sensing device of claim 1 wherein the membrane has a thickness of up to about 1.0 micron. 
     
     
       8. The oxygen sensing device of claim 7 wherein the membrane has a thickness of about 100 Angstroms.